The proceedings of NATO Advanced Research Institute (A.R.I.) on the efficiency of manufacturing systems are structured in four parts. Part I presents an overview of the A.R.I. and describes the structure of the week together with summaries of plenary expositions. The workshop reports are given in part II, and part III contains a summary of the final plenary discussion and some concluding remarks. Part IV contains the three theme papers together with the other papers which their authors presented briefly at the meeting.